type 2 diabetes causes a disproportionate health burden among racial and ethnic minorities in the United States. At the same time, these minority populations are among those most likely to be uninsured or to experience interruptions in healthcare coverage. Lack of insurance is associated with a greater probability of having undiagnosed diabetes, and with poorer quality of care for patients with diagnosed diabetes. As healthcare reform moves toward implementation following the passage of national legislation, important gaps remain in the understanding of the expected population health effects of expanding insurance coverage, and especially regarding the likely impact on health disparities. With respect to diabetes in particular, there is urgent need for a comprehensive analysis that traces the entire pathway from insurance to reduced morbidity and mortality, and provides a unifying framework for previous observational and quasi- experimental studies. The overall goal of this proposed study is to deploy systematic and rigorous empirical analysis to investigate the potential impact of expanding insurance coverage on health disparities in diabetes, at the national and state level. The project has three specific aims: 1) Quantify the potential impact of expanding insurance coverage among diabetic patients, in terms of improvements in key modifiable risk factors (e.g. high blood glucose) associated with major complications of diabetes, by racial and ethnic group. 2) Predict, based on alternative population risk factor distributions reflecting different insurance coverage scenarios, reductions in racial/ethnic disparities in diabetes-related morbidity and mortality attributable to expanded insurance coverage. 3) Evaluate the validity of the model results by comparing predicted and observed outcomes in Massachusetts following the expansion of insurance coverage through the landmark 2006 health reform. Collectively, the proposed research activities will constitute a coherent, significant and innovative advance in addressing critical gaps in policy-relevant information on diabetes disparities that are amenable to improvements through changes in the healthcare system. This information is essential for identifying key priorities and setting realistic targets for reducing health disparities, and for defining critical benchmarks for evaluating progress towards these objectives as major developments in national healthcare policy evolve.